Understanding the Science Behind Perovskite Solar Cells

NC State University researchers provide new insights that would enhance the synthesis and processing of perovskite solar cells.

A new technology holds the promise of the most cost-effective solar power, though it hasn’t been in development as long as silicon solar panels: Perovskite Solar Cells.

To date, when it comes to the most efficient solar panels, silicon-based cells are still the top option that also meets other industry scale requirements.

But in 2009, scientists from Japan were the first to demonstrate the application of halide perovskite salts for solar panels. Using dye-sensitized solar cells, the team achieved 3.8% power conversion efficiency.

In the decade since, researchers from around the world picked up from there, and the field saw significant progress. Although scientists were able to improve the performance of perovskite solar cells, no one was quite sure why it worked in the first place, until now.

Insights Into the Science of Perovskite Solar Cells

The optoelectronic properties of perovskites have been studied for years before 2009, for applications such as (LEDs) light-emitting diodes.

But halide perovskites became more recognized as photovoltaic materials, and they quickly gathered steam.

Experimental models of perovskite solar cells can already convert over 26% of sunlight into power, which is about the same upper conversion efficiency limit current silicon solar panels can achieve theoretically (26.6%). Perovskite solar devices can, in theory, convert 40% of sun rays into electricity.

Perovskite solar cells still have to prove their commercial viability and ability to meet large-scale demands like environmentally scalable production processes.

To do that, scientists have to gain a deep understanding of the chemical and physical workings of halide perovskite minerals.

“This is about material design. If you want to intentionally engineer halide perovskite solar cells that have the desirable characteristics you’re looking for, you have to understand not only how the material behaves under different conditions, but why,” says Aram Amassian, an associate professor of materials science and engineering.

Amassian and his colleagues at North Carolina State University have tackled an essential phenomenon about halide perovskites in solar panels that was previously obscure.

During the synthesis process, engineers add cesium and rubidium to make halide perovskites evenly distributed across the solar cell and make it more chemically homogeneous.

But they didn’t actually understand why that worked.

Amassian explains their findings, which were published in a paper in the journal Joule:

“Some of the precursors, or ingredients, want to form several compounds other than the one we want, which can cluster key elements irregularly throughout the material. That was something we didn’t know before. We also found that introducing cesium and rubidium into the process at the same time effectively suppresses the formation of those other compounds, facilitating the formation of the desired, homogeneous halide perovskite compound that is used to make high-performance solar cells.”

Now, the team has to figure out how to bring their findings out of the lab and apply them to real-world manufacturing conditions to enable large-scale production of perovskite solar cells.